Eukaryotes and Prokaryotes:
Unlike the nucleus of the multicellular organisms, the nucleus of the bacterial cell is not well-organised. They lack a nuclear membrane. Based on this, the cells are classified into two types. They are prokaryotic and eukaryotic cells.
Prokaryotic cells:
'Pro' refers to primitive, and 'karyon' refers to the nucleus. These cells lack a well-defined nucleus and organelles such as the plastids, mitochondria etc.
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Paramecium, Amoeba, Euglena  and more organisms like Bacteria, Chlamydomonas and Blue green algae.
'Eu' refers true, and 'karyon' refers to the nucleus. These cells have a well-organised nucleus with a nuclear membrane. They contain all the various cell organelles.
All organisms other than bacteria and blue green algae are called eukaryotes. Yeast is a unicellular eukaryote.
The sac-like-structures found mainly in the plant cells for the storage of food and water are known as vacuoles. In the plant cells, the vacuoles occupy most of the space. Whereas in animal cells they are much smaller, and help in the storage of wastes and excess water that has to be excreted.
Organelles of the plant cell:
Plastids and chloroplast:
The cell organelles that contain the pigments of different colours are known as plastids. Some of them are green in colour due to the presence of a green colour pigment known as chlorophyll. These green colour plastids are known as chloroplasts. These structures are responsible for the green colour of the leaves. Chlorophyll is the pigment that is essential for the process of photosynthesis.